The present invention relates to a process for preparing trione bis(oxime ether) derivatives of the formula I 
where the substituents have the following meanings:
R1,R3 are each unsubstituted, partially or fully halogenated C1-C6-alkyl or C3-C6-cycloalkyl;
R2,R4 are each unsubstituted C1-C4-alkyl or C2-C4-alkenyl-, C2-C4-alkynyl- or phenyl-substituted methyl and
x is oxygen or Nxe2x80x94OH.
Furthermore, the invention relates to ketals of the formula III, 
bisoxime ether ketals of the formula IV 
and bisoxime ether ketones of the formula Ia 
which are obtainable by this process.
Bisoxime ether ketones of the formula Ia and bisoxime ether oximes of the formula Ib are interesting intermediates for preparing the crop protection agents known from WO-A 97/15552. 
In the prior art, there are only a few documents dedicated to the synthesis of bisoxime or trisoxime derivatives of vicinal triketones. Furthermore, some of the in some cases older documents have inaccurate or erroneous structures (Gazz. Chim. Ital., 67 (1937), 388; Gazz. Chim. Ital., 52 (1922), 289). The structural elucidation of the complex mixtures of substances which are formed, for example, in the reaction of 3-(hydroxyimino)pentane-2,4-dione with hydroxylamine was only possible by modern analytical methods: in addition to the (E,E,E)- and (E,Z,E)-isomers of the pentane-2,3,4-trione trisoxime, cyclized furoxanes and isoxazoles are formed (J. Chem. Soc., Perkin Trans. II (1987), 523). Owing to the cyclic byproducts formed and the wrong regio- and stereochemistry, the substance mixtures obtained by the reaction of triketones and hydroxylamine are not suitable for synthesizing the trione bis(oxime ether) derivatives Ia and Ib.
A targeted synthesis of the bisoxime ether oximes Ib is described in WO 97/15552. 
This synthesis sequence has the disadvantage that the central oxime ether function (R2Oxe2x80x94Nxe2x95x90C) is only synthesized in the last step. Since the steric demand of the two substituents at the central carbon atom (R1xe2x80x94Cxe2x95x90NOR4 and R3xe2x80x94Cxe2x95x90NOH) differs only slightly, the oximation does not proceed in a stereoselective manner and, with regard to the bond R2Oxe2x80x94N, mixtures of isomers are formed which are difficult to separate.
It is an object of the present invention to provide a process which allows the synthesis of compounds of the formulae Ia and Ib in a targeted manner and which additionally affords the desired isomers of these compounds directly, i.e. without an isomer separation.
We have found that this object is achieved by the process mentioned at the outset, which comprises
1) reacting a dione of the formula II, 
where the substituents R1, R2 and R3 are each as defined above with an alcohol or diol in the presence of an acid to give the ketal of the formula III, 
where the substituents R5 and R6 are each C1-C6-alkyl, benzyl or C1-C3-haloalkyl or R5 and R6 together with the carbon and the two oxygen atoms of the ketal function form a ring A 
where the substituents and the index n have the following meanings:
R7,R8,R11,R12 are each hydrogen, halogen, C1-C4-alkyl, C1-C3-haloalkyl, C1-C4-alkoxymethyl, C2-C4-alkenyl, C2-C4-alkynyl or phenyl, where the latter may be substituted by nitro or halogen;
R9,R10 each have one of the meanings given for R7, R8, R11 or R12 and R9 and R10 together form an exo-methylene group or a carbonyl group and
n is 0,1 or 2,
2) converting the result ketal III
a) with an alkoxyamine of the formula R4Oxe2x80x94NH2, where R4 is as defined above, or one of its acid addition salts, or
b) with hydroxylamine or its acid addition salt and subsequent alkylation with an alkylating agent R4xe2x80x94L1, where R4 is as defined above and L1 is a nucleophilically replaceable leaving group, into the bisoxime ether ketal IV, 
where the substituents R1 to R6 are each as defined above, and
3) hydrolyzing the bisoxime ether ketal IV obtained in this manner in the presence of acid,
a) to give the bisoxime ether ketone Ia, 
xe2x80x83or
b) aminating it with hydroxylamine or its acid addition salt to give the bisoxime ether oxime Ib, 
By the process according to the invention, it is possible to synthesize, in a targeted manner, compounds of the formula Ia or Ib, depending in each case on the design of step 3). A further advantage of the process is the fact that the compounds Ia and Ib are obtained in isomerically pure form with regard to the central oxime ether unit.
A particular embodiment of the process is shown in scheme 1. 
By conducting the reaction in a suitable manner, it is possible to obtain preferably the E,E-isomer Iaxe2x80x2 and E,Z,E-isomer Ibxe2x80x2 via the bisoxime ether ketals IVxe2x80x2 (see scheme 1):
in step 1) diols, such as, for example, ethylene glycol, 1,3-propane diol or preferably 2,2-dimethyl-1,3-propanediol are employed which afford the cyclic ketals III.
the oximation step is carried out according to variant 2a). Specifically, the ketal III is reacted with an acid addition salt of the alkoxyamine R4Oxe2x80x94NH2 at 20-65xc2x0 C. and the acid which is released during the reaction is at least partially bound by addition of bases.
in step 3a)/3b), the hydrolysis/aminolysis is started at a pH of from 0.5-1.5 and at 20-400xc2x0 C.
If, on the other hand, for example dimethyl ketal IIIa ( R5, R6=methyl), which is hydrolyzed (step 3a) or aminated (step 3b) at temperatures above 40xc2x0 C., is used as starting material, the fractions of the Z-isomer Iaxe2x80x3 or Ibxe2x80x3 in the reaction mixture generally increase. 
The individual process steps are illustrated in more detail below.
1) Ketal Formation 
The ketal formation can generally be carried out with C1-C6-alkanols, such as, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, s-butanol, n-pentanol, with benzyl alcohol or with C1-C3-haloalkyl alcohols, such as, for example, 2,2,2-trichloroethanol. Particularly suitable are diols, such as, for example, o-dihydroxybenzene, ethylene glycol (1,2-ethanediol), 1-(2-nitrophenyl)-1,2-ethanediol, hex-5-ene-1,2-diol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-bromo-1,2-propanediol, 2-exo-methylene-1,3-propanediol, 2,2-dibromo-1,3-propanediol, 1,4-butanediol, 1,4-dimethoxy-2,3-butanediol. Particularly suitable are sterically demanding diols, such as 1,3-propanediol and 2,2-dimethyl-1,3-propanediol.
The ketal formation is generally carried out in the presence of acids, such as BF3xc3x97Et2O (Lewis acid) or preferably Bronstedt acids, such as sulfuric acid, hydrogen chloride, hydrogen bromide or hydrogen iodide, perchloric acid, orthophosphoric acid, polyphosphoric acid, p-toluenesulfonic acid, p-dodecylbenzenesulfonic acid or camphor sulfonic acid. Preference is given to using p-toluenesulfonic acid or sulfuric acid.
The acid is usually employed in catalytic amounts of from 0.05 to 2 mol % and preferably from 0.5 to 1 mol %, based on the dione II.
The reaction temperature generally depends on the nature of the alcohol employed and is generally 20-150xc2x0 C. and preferably 60-110xc2x0 C. When using diols, a temperature of 60-90xc2x0 C. has been found to be advantageous in many cases.
The water formed during the reaction is usually removed from the reaction mixture. To this end, the methods described in the prior art are employed (see, for example, Organikum, Barth Verlagsgesellschaft, Leipzig).
The water of reaction can, on the one hand, be removed using dehydrating agents, such as, for example, ortho esters. The ortho ester, such as, for example, trimethyl orthoformate, is generally employed in a concentration of from 1 to 1.5 molar equivalents. The reaction time is generally from 0.5 to 3 hours.
On the other hand, it has been found advantageous to remove the water of reaction using entrainers, such as toluene or cyclohexane. The end point of the reaction can be determined easily by the amount of water which is separated off. In some cases, it is advantageous to carry out the reaction at reduced pressure.
The preferred solvent is the alcohol that is required for the ketalization, which is in this case generally employed in excess. Good results were obtained using, for example, 1-10 molar equivalents of diol. If the ketalization is carried out by removal of water in the presence of an entrainer, the amount of diol can generally be reduced to 1-3 molar equivalents. Suitable solvents are furthermore hydrocarbons, such as, for example, toluene or cyclohexane, halogenated hydrocarbons, such as chlorobenzene or methylene chloride, amides, such as dimethylformamide, and ethers, such as diethyl ether or dioxane.
The reaction mixtures are worked up, for example, by extraction with a nonpolar solvent, such as an ether, halogenated hydrocarbon or, in particular, a hydrocarbon, such as cyclohexane. After the aqueous phase has been separated off, the organic phase can generally be employed directly in the subsequent oximation step. In many cases, it is not even necessary to exchange the solvent.
The diones of the formula II are known from the literature or can be prepared by methods known from the literature [cf. Indian J. Chem. B, (1991) 749-753; Bull. Acad. Sci. USSR Div. Chem. Sci. (Engl. Transl.) 28, (1979) 121-128; EP-A 416 857].
In particular, the diones II can be prepared by the procedure illustrated in more detail below.
The 1,3-diketones of the formula V 
are converted by nitrozation into compounds of the formula VI, 
where the substituents R1 and R3 in the formulae V and VI are as defined in claim 1.
The nitrozation is usually carried out using sodium nitrite in the presence of a carboxylic acid or mineral acid. Acetic acid, hydrochloric acid and in particular sulfuric acid are particularly suitable.
In general, the nitrozation is carried out at from xe2x88x9210 to 60xc2x0 C. and in particular at from 10 to 20xc2x0 C.
In general, the nitrozation is carried out at a pH of from 2 to 6 and in particular at a pH of from 4 to 5.
The following process variants were found to be particularly advantageous: i) the 1,3-diketone V is initially charged in aqueous sodium nitrite solution. The acid is then added dropwise at a pH of from 4 to 5; ii) the 1,3-diketone V is initially charged in water and the acid and the aqueous sodium nitrite solution are simultaneously metered in at a pH of from 4 to 5.
Furthermore, it may be advantageous to add an organic solvent in which the compound VI is soluble, at the beginning or the end of the reaction. The resulting solutions can be employed directly for the subsequent alkylation step. An intermediate isolation of the thermally and hydrolytically unstable compound VI can thus be avoided. In certain cases, it may furthermore be advantageous to replace the solvent used for the extraction of VI by a solvent which is more suitable for the alkylation. Solvents which are particularly suitable for the extraction are aprotic, if appropriate partially water-miscible solvents, for example halogenated hydrocarbons, such as methylene chloride, carboxylic esters, such as ethyl acetate, or ethers, such as methyl tert-butyl ether.
The alkylation of VI to the diones II can be carried out, for example, in alcohols, such as methanol, halogenated hydrocarbons, such as methylene chloride, carboxylic esters such as ethyl acetate, or ethers, such as methyl tert-butyl ether. Ketones, such as acetone, and amides, such as dimethylformamide or N-methylpyrrolidone, are particularly suitable.
Suitable alkylating agents are, for example, alkyl halides, tosylates and dialkyl sulfates. Dialkyl sulfates of the formula VII
(R2O)2SO2xe2x80x83xe2x80x83VII
in which the substituent R2 is as defined in claim 1 are particularly suitable.
The alkylation is usually carried out in the presence of bases, such as alkali metal or alkaline earth metal hydroxides, alkali metal or alkaline earth metal carbonates, alkali metal or alkaline earth metal alkoxides or tertiary amides.
The reaction temperature is generally from xe2x88x9220 to 100xc2x0 C. and preferably from xe2x88x9210 to 35xc2x0 C. and in particular from 0 to 25xc2x0 C.
Usually, the solvent and the base are initially charged, and compound VI and the alkylating agent are then metered in simultaneously or successively.
2) Oximation 
2a) The alkoxyamine R4Oxe2x80x94NH2 is employed either in the form of an acid addition salt or as free base, where the latter can be released from the salt by addition of a strong base.
Preference is given to using the acid addition salts of the alkoxyamine. All customary acids are suitable for preparing the acid addition salts. Hereinbelow, only a few examples are given: carboxylic acids, such as acetic acid or propionic acid, dicarboxylic acids, such as oxalic acid or succinic acid, mineral acids, such as phosphoric acid or carbonic acid, and in particular hydrochloric acid or sulfuric acid.
If the acid addition salts of the alkoxyamine are employed, it is generally advantageous to add a base to bind the acid which is released during the reaction. In many cases, a pH of from 2 to 5 and in particular of from 3 to 4 has been found to be advantageous for the oximation.
In general, from 1 to 2.5 molar equivalents of a base are added. Suitable bases are, in particular, pyridines, trialkylamines, sodium hydroxide, sodium acetate and sodium methoxide. If sodium acetate is used, it is customary to add glacial acetic acid.
Conversely, it is of course also possible to employ the alkoxyamine as free base and to use one of the abovementioned acids to set the abovementioned pH range.
Suitable solvents are, for example, the solvents described in the preceding step. Also suitable are carboxylic acids, such as acetic acid, ethers, such as tetrahydrofuran, diethyl ether, methyl tert-butyl ether, or else water/pyridine mixtures. Particularly suitable are alcohols, such as methanol, ethanol, n-propanol or isopropanol.
It has furthermore been found to be advantageous to use the solvent employed in the ketalization, or the solvent mixture which is present after work-up of the ketals III, for the oximation step, too. If appropriate, it may be expedient to add other solvents to the mixture. Thus, steps 1) and 2) can be carried out as a one-pot variant.
The reaction temperature is generally from xe2x88x9220 to 150xc2x0 C. and preferably from 0 to 100xc2x0 C. and in particular from 20 to 65xc2x0 C.
2b) The procedure described under 2a) can also be carried out in two steps, by firstly reacting the ketal III with hydroxylamine or its acid addition salt and subsequent alkylation with R4xe2x80x94L1. With regard to the way the reaction is carried out, the statements made above apply.
The reaction mixture is preferably worked up as described in the preceding step, by extractive methods.
3) Ketal Cleavage: (a) Hydrolysis and (b) Amination 
The ketal is generally cleaved in an acidic medium. A pH of from 0 to 2 and preferably from 0.5 to 1.5 has been found to be advantageous.
The pH range mentioned above can be set using any customary acid. Acetic acid, hydrochloric acid or sulfuric acid, for example, have been found to be suitable.
The cleavage of the ketal can be carried out with or without addition of a solvent. It has been found to be advantageous to use organic solvents which are stable in the abovementioned pH range (for example ethyl acetate). It may also be advantageous to use a solvent which is monophasically miscible with water/acid. Particularly suitable here are alcohols, such as, for example, methanol. The cleavage of the ketal can be carried out advantageously, for example, in water/methanol/glacial acetic acid (a suitable mixing ratio is, for example: 1/1/0.2) or ethyl acetate/water mixtures.
The aminolysis to give the compounds Ib is carried out under the conditions mentioned for the ketal cleavage, but in the presence of hydroxylamine or its acid addition salt. All customary acids are suitable for preparing the acid addition salts. Hydrochloric acid or sulfuric acid have been found to be particularly advantageous.
The hydroxylamine or its acid addition salt is generally employed in a ratio of from 1 to 2 and preferably from 1 to 1.3 molar equivalents, based on the bisoxime ether ketal IV.
The reaction temperature is generally 0-150xc2x0 C. Lower reaction temperatures of from 20 to 40xc2x0 C. have been found to be particularly advantageous for preparing the isomers Iaxe2x80x2 and in particular Ibxe2x80x2. At high reaction temperatures ( greater than 40xc2x0 C.), the proportion of the isomers Iaxe2x80x3 and Ibxe2x80x3 generally increases.
Work-up of the reaction mixtures is preferably carried out as described in the two preceding steps, by extraction.
The compounds of the formula Ib can be purified, for example, via their sodium salt. By adding a base, the oximes can be converted into the corresponding salt. The bisoxime ether oxime Ib can subsequently be rereleased by subsequent acidification from the salt which has been, if appropriate, separated off or purified.
The process according to the invention is particularly suitable for preparing ketals of the formula III, 
bisoxime ether ketals of the formula IV 
and bisoxime ether ketones of the formula I 
where the substituents each have the following meanings:
R1,R3 are each unsubstituted, partially or fully halogenated C1-C6-alkyl or C3-C6-cycloalkyl;
R2,R4 are each unsubstituted C1-C4-alkyl or C2-C4-alkenyl-, C2-C4-alkynyl- or phenyl-substituted methyl;
X is oxygen or Nxe2x80x94OH;
R5,R6 are each C1-C6-alkyl, benzyl or C1-C3-haloalkyl or
R5,R6 together with the carbon and the two oxygen atoms of the ketal function form a ring A, 
where the substituents and the index n have the following meanings:
R7,R8,R11 ,R12 are each hydrogen, halogen, C1-C4-alkyl, C1-C3-haloalkyl, C1-C4-alkoxymethyl, C2-C4-alkenyl, C2-C4-alkynyl or phenyl, where the latter may be substituted by nitro or halogen;
R9,R10 each have one of the meanings given for R7, R8, R11 or R12 and R9 and R10 together form an exo-methylene group or a carbonyl group and
n is 0,1 or 2.
Suitable intermediates for preparing the compounds IV (where R4 is not hydrogen) may be compounds of the formula IV in which R4 is hydrogen (cf. formula Iva).
In the definitions of the compounds I, II and IV given above, collective terms which represent individual enumerations of each of the group members were used for the radicals R1 to R12. The radicals alkyl, alkenyl or alkynyl can be straight-chain or branched.
The term xe2x80x9cpartially or fully halogenatedxe2x80x9d is intended to express that in the groups thus characterized some or all of the hydrogen atoms may be replaced by identical or different halogen atoms.
The term xe2x80x9chalogenxe2x80x9d represents in each case fluorine, chlorine, bromine or iodine.
Examples of other meanings are:
C1-C4-alkyl:
methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl and 1,1-dimethylethyl;
C1-C6-alkyl:
C1-C4-alkyl as mentioned above, and also pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1-ethyl-1-methylpropyl and 1-ethyl-3-methylpropyl;
C1-C3-haloalkyl:
a C1-C3-alkyl radical as mentioned above which is partially or fully substituted by fluorine, chlorine, bromine and/or iodine, i.e., for example, chloromethyl, dichloromethyl, trichloromethyl, fluoromethyl, difluoromethyl, trifluoromethyl, chlorofluoromethyl, dichlorofluoromethyl, chlorodifluoromethyl, 2-fluoroethyl, 2-chloroethyl, 2-bromoethyl, 2-iodoethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl, 2-chloro-2-fluoroethyl, 2-chloro-2,2-difluoroethyl, 2,2-dichloro-2-fluoroethyl, 2,2,2-trichloroethyl, pentafluoroethyl, 2-fluoropropyl, 3-fluoropropyl, 2,2-difluoropropyl, 2,3-difluoropropyl, 2-chloropropyl, 3-chloropropyl, 2,3-dichloropropyl, 2-bromopropyl, 3-bromopropyl, 3,3,3-trifluoropropyl, 3,3,3-trichloropropyl, 2,2,3,3,3-pentafluoropropyl, heptafluoropropyl, 1-(fluoromethyl)-2-fluoroethyl, 1-(chloromethyl)-2-chloroethyl, 1-(bromomethyl)-2-bromoethyl;
C1-C4-alkoxy in the alkoxy moiety of C1-C4-alkoxymethyl:
methoxy, ethoxy, propoxy, 1-methylethoxy, butoxy, 1-methylpropoxy, 2-methylpropoxy and 1,1-dimethylethoxy;
C2-C4-alkenyl: ethenyl, prop-1-ene-1-yl, prop-2-ene-1-yl, 1-methylethenyl, but-1-ene-1-yl, but-2-ene-1-yl, but-3-ene-1-yl, 1-methyl-prop-1-ene-1-yl, 2-methyl-prop-1-ene-1-yl, 1-methyl-prop-2-ene-1-yl and 2-methyl-prop-2-ene-1-yl;
C2-C4-alkynyl: ethinyl, 1-propinyl, 2-propinyl, 1-butinyl, 2-butinyl, 3-butinyl, 1-methyl-2-propinyl;
C3-C6-cycloalkyl: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl.
With a view to their suitability as intermediates for preparing the crop protection agents known from WO-A 97/15552, particular preference is given to the compounds of the formulae I, III and IV having the following substituents, the preference existing in each case alone or in combination:
R1, R3 are each methyl, ethyl, trifluoromethyl or trichloromethyl and in particular methyl or ethyl;
R2, R4 are each methyl, ethyl, benzyl or propargyl and in particular methyl;
X is oxygen or Nxe2x80x94OH;
R5, R6 are each methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl or benzyl and in particular
R5, R6 together with the carbon and the two oxygen atoms of the ketal function form a ring A 
where the substituents and the index n have the following meanings:
R7,R8,R11 ,R12 are each hydrogen, bromine or methyl and preferably hydrogen or methyl;
R9,R10 each have one of the meanings given for R7, R8, R11 or R12 and
n is 0 or 1 and in particular 1.
With a view to their suitability as intermediates for preparing the crop protection agents known from WO-A 97/15552, preference is furthermore given to the compounds of the formulae IVxe2x80x2, Iaxe2x80x2 and Ibxe2x80x2.